"That's Dory," said 4-year-old Idris Madison, pointing to the royal blue tang in the aquarium at Center City Pediatrics. And the orange clownfish? "Nemo," he said shyly.

Finding Dory, the sequel to the 2003 Pixar hit, Finding Nemo, was released in theaters on Friday. When Nemo came out, sales of the orange clownfish, the fish Nemo was based on, shot up. The same reaction is expected this time.

But beware: the real-life Dory, unlike the gentle clownfish, is not a fish for the faint-hearted.

"Dory gets much, much bigger, gets more aggressive, it needs a bigger tank,'' said John Nixon, who works at Captain Nemo's Aquarium Superstore in Norriton. "This fish could be a psycho killer if it's put in a tank that's too small."

The animated Dory, voiced by Ellen DeGeneres, is a sweet-but-forgetful character. Is the real Dory more like Marvel's sexy-but-lethal Wolverine?

"It's not the case at all", said Jon Gordon, owner of TerraReef Aquariums in Wilmington. "They just have to assert their dominance."

Still, he said, "I wouldn't keep two (blue tangs) together. Animals from the same genus don't do well together. They posture a lot to prove who's the dominant one, and that typically doesn't work well for them."

When it doesn't work well, blue tangs stab each other with the lethal, razor-sharp spines at the base of their tails. The spines are so sharp, blue tangs belong to a group called surgeonfish.

These spines also can get caught in nets or cut your hand open. "Not wise for a touch tank," said Gordon.

Another drawback to bringing home your own "Dory": blue tang get big. They grow to almost a foot in length in about two years. And they're avid swimmers.

"They need room to turn around," said Gordon. So a small, home tank will not work.

They also need a lot of fuel.

"You need to feed them at least three times a day," said Gordon. And not just a sprinkle of fish flakes. "They're primarily eating meaty foods, especially when they're younger."

Gordon said tangs are best kept in conditions similar to those found in the wild. This is comparable to keeping a coral reef tank, which can prove challenging to new aquarium keepers.

So how much does all this cost?

"I tell them to buy a 210-gallon tank," said Nixon. That and the other gear will cost at least $3,000. And the fish? Nixon said the price of the royal blue tang at his store ranges from $60 to $250, depending on the season and the size of the fish. The fish are cheapest in the fall, when they are more abundant.

Gordon, who deals in high-end aquarist gear, put the tank cost at around $10,000, and estimated it may be six months or more before the tank has the proper environmental conditions for the sensitive tang.

"Just in the last week or two, people with kids have been talking about" the fish, Nixon said.

"It's not my place to make decisions for people. I just give them the info. They're gonna do what they're gonna do."

Pre-movie release, Gordon hadn't heard from many prospective blue tang owners, but he's bracing to explain the ethics of keeping these delicate fish at home.

Gordon said he hopes moviegoers pay attention to the coral reefs where Dory, Nemo and their fishy bretheren live. "Our carbon footprint is causing ocean acidification, which is stopping the corals from growing. Doomsday scenario is what scientists are talking about."

He's excited about conservation efforts by groups like Rising Tide Conservation (http://risingtideconservation.org/), which is working to breed marine fish in captivity. Blue tangs are still collected from the wild, and unless they come from managed supply chains, the way they are collected is unregulated. Cyanide squirted into the water had been one way to collect aquarium fish. Gordon said he makes sure his fish don't come from suppliers who do this, but ideally all aquarium fish will someday be bred in captivity, a more eco-friendly alternative than collecting from the wild.

Matthew Ferroni, Supervisor of Fish and Invertebrate Department at Adventure Aquarium in Camden, agreed that royal blue tang are not ideal for novices.

"People need to be responsible pet owners. Know what the requirements are. People are not purchasing a character, it's a wild animal. People can get a great experience visiting a pet shop or local aquarium."